Thanks alot for all your help guys, although i managed to fix it myself.
michaelk i couldnt see the boot menu, i actully saw:
error: unknown filesystem
grub rescue >
There was a 150gb unallocated partition, i wanted this to be back into my orignal C drive in windows, so i was just messing round with it to fix it lol
Since i could boot ubuntu live disk, i reinstalled the O/S on entire disk, this sorted the bootmenu but also removed windows, so i ran a deep format boot disk (as it still wouldnt let me format using the original windows disk due to not finding a partition, i believe this was because of the ubuntu superblocks). The deep format took around 3-5 hours to do. it finally allowed me to install windows after this. i'm going to be looking at some guides on how to install ubuntu and windows correctly without causing problems like this again.